JP2016206347A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus which can perform optimum distribution of an air capacity so as to properly perform collection of UFP (Ultra-Fine Particles) and cooling of sheets.SOLUTION: An image formation apparatus 1 comprises: a first duct 202 which has one end connected to a fixation unit 80 and sucks UFP discharged from the fixation unit 80; a second duct 203 which has one end connected to a sheet discharge part 201 and sucks heat emitted from a sheet S located in the sheet discharge part 201; a suction part 206 which draws in air from the fixation unit 80 and the sheet discharge part 201 through the first duct 202 and the second duct 203; an air capacity adjustment member 206 which adjusts distribution of the air capacity to the fixation unit 80 and the sheet discharge part 201; and a control part 30 which controls the air capacity adjustment member 206. The control part 30 performs control so as to adjust distribution of the air capacity according to a necessary air capacity of the fixation unit 80 and the sheet discharge part 201 to the air capacity adjustment member 206 at the time of consecutive printing to the sheets S.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile machine.

  In an electrophotographic image forming apparatus, an air flow is formed inside the image forming apparatus using a fan and a duct for cooling the inside of the image forming apparatus, cooling the paper, collecting chemical substances, and collecting dust. It is generally done.

  In the image forming apparatus, when the printing speed is increased and the productivity of double-sided printing is improved, the toner image fixed on the paper melts and adheres to other paper due to the heat of the paper after fixing, so-called The problem of “tacking” occurs. In order to prevent this tacking, it is effective to apply air to the paper after fixing to remove heat from the paper.

  In an electrophotographic image forming apparatus, it is known that several kinds of chemical substances (chemical emission) are released during image formation. Typical chemical substances to be released include ozone generated when the photosensitive member is charged and toner dust generated during development or fixing. Conventionally, the generated toner dust is sucked and collected by a filter to prevent it from being released to the outside of the image forming apparatus.

  Among the released chemical substances, ultra-fine particles (ULTRA-Fine Particles; having a diameter of 100 nm or less, hereinafter referred to as “UFP”) from an electrophotographic image forming apparatus as the global environmental protection awareness increases. The occurrence of the problem has been raised as an issue. Japanese Patent Laying-Open No. 2011-180235 (Patent Document 1) discloses that an electrophotographic image forming apparatus generates UFP mainly in a fixing unit. Therefore, the image forming apparatus disclosed in Patent Document 1 employs a configuration in which UFP is sucked from the fixing unit and collected by a filter.

  In the above-described electrophotographic image forming apparatus, it is necessary to use airflow for various purposes, and it is also necessary to cope with new problems such as UFP recovery. On the other hand, the size and quantity of the fan that generates the airflow are limited from the viewpoints of downsizing of the image forming apparatus, cost reduction, environmental and noise considerations, and the like.

  Patent Document 1 proposes a configuration in which UFP collection and sheet cooling are made compatible by a single fan by switching the air path and the air direction. Specifically, an air path for UFP recovery is formed from the fixing unit toward the fan during the initial fixing heating, where the amount of UFP diffused is large, and after a predetermined time, the air flows from the fan toward the paper discharge unit. By changing the direction and path, the air path for cooling the sheet is switched.

JP 2011-180235 A JP 2008-170629 A

  However, during continuous printing, the release of UFP from fixing continues even though it decreases with time. In order to reliably prevent tacking, it is effective to cool the sheet from the start of sheet discharge. In view of the above, the configuration of Patent Document 1 in which airflow is formed only in one of UFP recovery and sheet cooling is not a sufficient configuration. Also, in Japanese Patent Application Laid-Open No. 2008-170629 (Patent Document 2), the configuration in which air blows out from the paper discharge unit gives the user unpleasant feeling, and from this point of view, too much air should not be blown onto the paper discharge unit. .

  An object of the present invention has been made in view of the above problems, and provides an image forming apparatus capable of optimally distributing the air volume so that UFP recovery and sheet cooling can be performed appropriately. For the purpose.

  The image forming apparatus of the present invention is an image forming apparatus including a fixing unit and a paper discharge unit, one end of which is connected to the fixing unit and sucks UFP discharged from the fixing unit, and one end of which is connected to the fixing unit. A second duct that is connected to the paper discharge unit and sucks heat released from the paper located at the discharge unit, and draws air from the fixing unit and the paper discharge unit through the first duct and the second duct. A suction unit for adjusting the air volume distribution to the fixing unit and the paper discharge unit, and a control unit for controlling the air volume adjustment member. During the continuous printing, the air volume adjusting member is controlled to distribute and adjust the air volume according to the air volumes required for the fixing unit and the paper discharge unit.

  In another aspect, the present invention includes a merging portion to which the other end of the first duct and the other end of the second duct are connected, and the merging portion is provided with the air volume adjusting member, and the first duct and the second duct The air flowing inside the two ducts is in the same direction.

In another embodiment, the suction part is provided on the downstream side of the joining part.
In another form, the said control part controls the said air volume adjustment member so that the air volume of the air which flows through the inside of the said 1st duct and the said 2nd duct does not become 0% in all.

  In another form, the said control part controls the said air volume distribution adjustment according to the integration time from the start of continuous printing.

  In another embodiment, the control unit controls the air volume distribution adjustment according to the total number of sheets from the start of continuous printing.

  In another aspect, the paper discharge unit includes a paper discharge tray and a detection unit that detects the amount of paper stacked on the paper discharge tray, and the control unit is configured to detect the paper stack amount detected by the detection unit. In response to the above, the air volume distribution adjustment is controlled.

  In another embodiment, the control unit acquires information on single-sided printing or double-sided printing on paper, and in the case of single-sided printing, priority is given to UFP collection over paper cooling in the control of air volume distribution adjustment. Take control.

  In another aspect, the image forming apparatus further includes an internal temperature detecting unit that detects an internal temperature of the image forming apparatus, and the control unit acquires information on single-sided printing or double-sided printing on paper, and performs double-sided printing. When the temperature information is acquired by the internal temperature detection means and becomes higher than a predetermined threshold temperature, control for giving priority to sheet cooling over UFP recovery is performed in the control of air volume distribution adjustment.

  In another aspect, the apparatus further includes an external paper discharge unit, and the control unit determines whether or not the external paper discharge unit is attached and determines that the external paper discharge unit is attached. Performs control to give priority to UFP collection over sheet cooling.

  In another embodiment, the image forming apparatus further includes an external temperature detection unit that detects an external temperature of the image forming apparatus, and the control unit acquires temperature information by the external temperature detection unit, and becomes higher than a predetermined threshold temperature. In this case, in the air volume distribution adjustment control, the paper cooling is prioritized over the UFP recovery. When the temperature is lower than a predetermined threshold temperature, the air volume distribution adjustment control is performed over the paper cooling. Control that prioritizes UFP collection is performed.

  In another aspect, the paper discharge unit includes a width size detection unit that detects a width size of the paper, and the control unit distributes the air volume according to the width of the paper detected by the width size detection unit. Control the adjustment.

  In another embodiment, when the sheet does not pass through the sheet discharge unit, the control unit performs control to give priority to UFP collection over sheet cooling in the control of the air volume distribution adjustment.

  In another embodiment, the control unit obtains information on color printing or black and white printing, and in the case of black and white printing, in the control of the air volume distribution adjustment, control for giving priority to UFP collection over sheet cooling is performed.

  In another embodiment, the control unit obtains information on color printing or monochrome printing, and in the case of monochrome printing, performs control that prioritizes sheet cooling over UFP collection in the control of air volume distribution adjustment.

  In another form, when the low speed mode in which the paper transport speed is slow is selected, the control unit performs control to give priority to UFP collection over paper cooling in the control of the air volume distribution adjustment.

  In another embodiment, the control unit prioritizes when the factors overlap with each other in determining whether to prioritize sheet cooling or UFP recovery in the control of air volume distribution adjustment. The ratio is stored in a table, and the air volume distribution adjustment is controlled based on the table.

  According to the present invention, it is possible to provide an image forming apparatus capable of optimally distributing the air volume so that the UFP can be properly collected and the sheet can be cooled.

1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus according to an embodiment. FIG. 3 is a first schematic diagram illustrating a fixing unit of the image forming apparatus and an exhaust mechanism of a paper discharge unit in the embodiment. FIG. 6 is a second schematic diagram illustrating a fixing unit of the image forming apparatus and an exhaust mechanism of a paper discharge unit in the embodiment. In the image forming apparatus according to the embodiment, when the “continuous print number”, “time”, or “discharge tray” of the image forming apparatus is used as a parameter on the horizontal axis, “UFP emission amount”, “new discharge temperature” And “the air volume ratio”. FIG. 4 is a diagram showing a table used when air volume distribution adjustment is controlled in the image forming apparatus according to the embodiment.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.

(Image forming apparatus 1)
With reference to FIG. 1, a schematic configuration of an image forming apparatus 1 according to the embodiment will be described. FIG. 1 is a cross-sectional view illustrating the overall configuration of the image forming apparatus 1. The image forming apparatus 1 in the embodiment is a tandem color digital copying machine. The image forming apparatus 1 includes an image reader unit 10 that reads a document image, and a printer unit 20 that prints the read image on a sheet S and reproduces it.

  The image reader unit 10 has a configuration in which an image of a document placed on a document glass plate (not shown) is read by moving a scanner. The original image is color-separated into three colors of red (R), green (G), and blue (B) and converted into an electrical signal by a CCD image sensor (hereinafter referred to as “CCD sensor”). Thus, red (R), green (G), and blue (B) image data of the document is obtained.

  The image data for each color component obtained by the image reader unit 10 is subjected to various data processing in the control unit 30, and further each of yellow (Y), magenta (M), cyan (C), and black (K). Reproduced color image data (hereinafter, each of the reproduced colors of yellow, magenta, cyan, and black is represented as Y, M, C, and K, and the number of the component related to each reproduced color is indicated by Y, M, C and K are added as subscripts).

  The image data is stored for each reproduction color in the image memory 33 in the control unit 30 and is read for each scanning line in synchronism with the supply of the paper S after being subjected to the necessary image correction for misregistration correction. And is a drive signal for a light emitting diode (LED).

  The printer unit 20 forms an image by an electrophotographic method, and an intermediate transfer belt 103 is stretched around a driving roller 61 and a driven roller 62 in the intermediate transfer unit 60. A tension is applied to the intermediate transfer belt 103 by urging the driven roller 62 in the left direction in the drawing by a spring (not shown).

Polycarbonate, polyimide, polyamideimide, or the like can be used as the material of the intermediate transfer belt 103. In this embodiment, polyamideimide having a surface resistance of about 10 ¹⁰ Ω / □ is used as an example.

  The drive roller 61 is rotated counterclockwise by the transfer drive motor 34 to drive the intermediate transfer belt 103. An encoder 341 is provided between the drive roller 61 and the transfer drive motor 34 to detect rotation unevenness of the drive roller and perform feedback control.

  Further, the printer unit 20 faces the intermediate transfer belt 103 and extends from the intermediate transfer belt cleaner side (hereinafter simply referred to as “upstream side”) to the conveyance side of the paper S (hereinafter simply referred to as “downstream side”). Image forming units 40Y, 40M, 40C, and 40K for Y, M, C, and K colors arranged at predetermined intervals, and transfer rollers 45Y, 45M, 45C, and 45K that transfer the toner image on the photosensitive member to the intermediate transfer belt 103. A secondary transfer roller 104 that secondarily transfers the toner image on the intermediate transfer belt 103 onto the paper S, a secondary transfer drive motor 35 that drives the secondary transfer roller 104, and residual toner on the intermediate transfer belt 103. A fixing unit having an intermediate transfer belt cleaner 105 to be removed, a paper feeding unit 50 arranged on the upstream side of the paper conveying unit, and a known fixing roller 80r arranged on the downstream side. It includes a door 80, a.

  Further, the panel unit 200 displays the operation of the image forming apparatus 1, the paper jam of the printer unit, the service life, and the like.

  Each of the image forming units 40Y, 40M, 40C, and 40K includes an exposure scanning unit 70Y, 70M, 70C, and 70K and an image processing unit.

  The exposure scanning units 70Y, 70M, 70C, and 70K include light emitting diodes (LEDs) 46Y, 46M, 46C, and 46K that emit light in response to the drive signal output from the control unit 30.

  The image processing unit includes photosensitive drums 41Y, 41M, 41C, and 41K, charging chargers 42Y, 42M, 42C, and 42K, and developing units 43Y, 43M, 43C, and 43K arranged around the photosensitive drums 41Y, 41M, 41C, and 41K. , Cleaners 44Y, 44M, 44C, 44K and the like.

  The paper feeding section 50 is for feeding a paper feed cassette 51 for storing the paper S, a paper feed roller 52 for feeding the paper S from the paper feed cassette 51, and a timing for feeding the paper S to the intermediate transfer belt 103. A sheet detection sensor SE1 for detecting the leading edge of the sheet S is provided immediately upstream of the registration roller 53.

  When the leading edge of the sheet S reaches the registration roller 53, it is detected by the sheet detection sensor SE1, so that the control unit 30 receives this detection signal and takes the timing to drive the registration roller 53 (not shown). A leading edge registration roller signal is generated to start feeding by the registration roller 53, and the sheet S is fed toward the intermediate transfer belt 103.

  The light emitting diodes (LEDs) 46Y, 46M, 46C, and 46K of the exposure scanning units 70Y, 70M, 70C, and 70K emit light in response to the drive signals from the control unit 30, respectively. , 41M, 41C, and 41K are exposed and scanned, respectively.

  The photosensitive drums 41Y, 41M, 41C, and 41K have the remaining toner on the surface removed by the cleaners 44Y, 44M, 44C, and 44K before being exposed. Further, the photosensitive drums 41Y, 41M, 41C, and 41K are uniformly charged by the chargers 42Y, 42M, 42C, and 42K after being discharged by irradiating an eraser lamp (not shown). When exposed to the LED light in such a uniformly charged state, electrostatic latent images are formed on the surfaces of the photosensitive drums 41Y, 41M, 41C, and 41K.

  The electrostatic latent images are developed by developing units 43Y, 43M, 43C, and 43K for the respective colors, whereby yellow (Y), magenta (M), cyan (on the surfaces of the photosensitive drums 41Y, 41M, 41C, and 41K). C) A black (K) toner image is formed. A voltage is applied to the transfer rollers 45Y, 45M, 45C, and 45K from a high voltage substrate (not shown), and the toner images on the photosensitive drums 41Y, 41M, 41C, and 41K are sequentially transferred onto the intermediate transfer belt 103.

  At this time, the image forming operation for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is transferred to the same position of the intermediate transfer belt 103 to which the toner image is conveyed. The image formed on the intermediate transfer belt 103 is conveyed to the secondary transfer unit, where the secondary transfer is performed on the paper S.

  The transfer rollers 45Y, 45M, 45C, 45K and the secondary transfer roller 104 are elastic rollers obtained by adding an ionic conductive material to NBR rubber and foaming it. Since the electrical resistance of the elastic roller changes due to the influence of temperature and humidity, the temperature and humidity are measured by a temperature / humidity sensor 54 provided in the image forming apparatus 1, and currents of appropriate transfer rollers 45Y, 45M, 45C, and 45K are measured. The voltage applied to each roller is adjusted so that the current of the secondary transfer roller 104 becomes the current. Further, the secondary transfer roller 104 is provided with a pressure contact / separation mechanism (not shown), and is separated from the belt when printing is not performed to prevent creep deformation of the elastic body.

  The sheet S on which the toner images of the respective colors are transferred is conveyed to the fixing unit 80 where the toner particles on the surface of the sheet S are melted and adhered to the surface of the sheet S to be fixed. Thereafter, the paper passes through a paper discharge unit 82 having a paper discharge roller 82 r and is discharged onto the paper discharge tray 81. Further, residual toner (hereinafter referred to as waste toner) remaining on the intermediate transfer belt 103 after being secondarily transferred to the sheet S in the secondary transfer portion is scraped off by the cleaning blade 68. The waste toner is conveyed to the front side of the intermediate transfer unit 60 by a screw 66 that rotates in the cleaner housing 69, and is sent to the waste toner box 108 via the joint 107.

(Exhaust mechanism of fixing unit 80 and paper discharge unit 201)
Next, with reference to FIG. 2, the fixing unit 80 and the exhaust mechanism of the paper discharge unit 201 provided in the image forming apparatus 1 of the present embodiment having the above-described configuration will be described. 2 and 3 are first and second schematic views showing the exhaust mechanism of the fixing unit 80 and the paper discharge unit 201. FIG.

  One end of a UFP duct 202 as a first duct for collecting UFP discharged from the fixing unit 80 is connected to the fixing unit 80. One end of a paper discharge duct 203 as a second duct for recovering heat released from the paper S is connected to the paper discharge unit 82 having a paper discharge roller 82r.

  The paper discharge duct 203 not only collects heat released from the paper S of the paper discharge unit 82 but also collects heat released from the paper S discharged and accumulated on the paper discharge tray 81. In this embodiment, an area including the paper discharge tray 81 and the paper discharge unit 82 is referred to as a paper discharge unit 201, and the paper discharge duct 203 collects heat released from the paper discharge unit 201, and the paper discharge unit 201. Cool the paper located at.

  The other ends of the UFP duct 202 and the paper discharge duct 203 communicate with a merging duct 205 constituting the merging portion 204. One end of the junction duct 205 is connected to the UFP duct 202 and the paper discharge duct 203. The merge duct 205 is provided with an air volume adjusting member 206 as an air volume adjusting member for adjusting the air volume of the air flowing through the UFP duct 202 and the paper discharge duct 203. The air volume adjusting member 206 is provided such that a plate-like valve body is movable by a driving device with the rotation center P1 as an axis center. Positioning control of the air volume adjusting member 206 is executed by the control unit 30 described later.

  The merging duct 205 is provided with a suction portion 207 on the downstream side of the air volume adjusting member 206 when viewed in the air flow direction. The suction unit 207 has a fan 207 a, one end connected to the junction unit 204, and the other end connected to the filter unit 300. The filter unit 300 includes a filter 300 f that captures UFP, one end is connected to the suction unit 207, and the other end is led out of the image forming apparatus 1.

  The suction unit 207 sucks air from the merging unit 204 toward the filter unit 300. In the paper discharge unit 201, (high temperature) air around the paper S is sucked through the paper discharge duct 203 and the junction unit 204. In the fixing unit 80, UFP generated from the fixing unit 80 is sucked through the UFP duct 202 and the junction unit 204.

  By adopting the above configuration, the air flowing through each of the UFP duct 202 and the paper discharge duct 203 flows in the same direction, and the air volume adjusting member 206 is provided in the merging portion 204, and the air volume is distributed between the plurality of ducts. Makes it easy to adjust.

  When the direction of air flow is set to the direction toward the paper discharge unit 201, the paper discharge unit 201 is a location accessible to the user, which may cause discomfort to the user. However, in the above configuration, the suction unit 207 is arranged such that the air flows in the direction from the paper discharge unit 201 toward the suction unit 207 and the direction from the fixing unit 80 toward the suction unit 207. Thus, exhausting to an area that is not accessed by the user does not cause discomfort to the user.

  Both the positioning control of the air volume adjusting member 206 and the operation control of the fan 207a are executed by the control unit 30. The control unit 30 performs control to distribute and adjust the air volume according to the air volume required for each of the fixing unit 80 and the paper discharge unit 201 during continuous printing by the image forming apparatus 1. Specifically, the control unit 30 adjusts the inclination angle of the air volume adjusting member 206 to determine the cooling paper volume distribution rate of the discharged paper by the UFP duct 202 and the air volume distribution rate of the UFP recovery by the paper discharge duct 203. To do. The control unit 30 moves the air volume adjusting member 206 to either the first state or the second state according to the state of the image forming apparatus 1.

(First state: UFP recovery has priority over paper cooling)
In the state shown in FIG. 2, the air volume adjusting member 206 is controlled to the first state. In the first state, the airflow adjustment member 206 controls the inclination angle of the airflow adjustment member 206 so that the passage cross-sectional area of the paper discharge duct 203 is narrowed and the passage cross-sectional area of the UFP duct 202 is widened. The cooling paper volume distribution rate of the discharged paper by the UFP duct 202 and the air volume distribution rate of the UFP recovery by the paper discharge duct 203 are determined so that UFP recovery takes priority over cooling. As shown in FIG. 5 described later, the air volume distribution rate can be set between a cooling duct air volume distribution rate and a UFP recovery air volume distribution rate. The same applies hereinafter.

(Second state: cooling paper prior to UFP recovery)
In the state shown in FIG. 3, the air volume adjusting member 206 is controlled to the second state. In the second state, the airflow adjustment member 206 increases the passage cross-sectional area of the discharge duct 203, and the inclination angle of the airflow adjustment member 206 is controlled so that the passage cross-sectional area of the UFP duct 202 becomes narrower. The cooling duct air volume distribution rate of the discharged paper by the UFP duct 202 and the air volume distribution rate of UFP recovery by the paper discharge duct 203 are determined so that the cooling of the paper has priority over the recovery.

  Next, the operation of the control unit 30 of the image forming apparatus 1 having the above configuration will be described with reference to FIG. FIG. 4 shows “UFP emission amount”, “new temperature for discharge”, and “new temperature for discharge” when “continuous print number”, “time”, or “discharge tray” of the image forming apparatus 1 is set as a parameter on the horizontal axis. It shows the relationship of “air volume ratio”.

  The control unit 30 of the image forming apparatus 1 according to the present embodiment distributes the air volume to the air volume adjusting member 206 in accordance with the air volumes required for the fixing unit 80 and the paper discharge unit 201 during continuous printing on paper. Control to adjust.

  For example, the control unit 30 may control the air volume adjusting member 206 so that the air volume of the air flowing inside the UFP duct 202 and the paper discharge duct 203 does not become 0%. As shown in FIG. 4, when continuous printing by the image forming apparatus 1 is started, it is necessary to give priority to the collection of UFP because the amount of UFP is diffused. However, since the temperature of the discharged paper is high, the air volume of the discharge duct 203 is Do not become 0%. For example, as shown in FIG. 2, a first state in which recovery of UFP is prioritized over cooling of paper S may be set.

  Although it is true that the amount of UFP diffused at the end of continuous printing is smaller than that at the start, the amount of UFP diffused is not 0%. It is advisable to avoid 0%. For example, as shown in FIG. 3, the second state where the cooling of the paper S is prioritized over the recovery of the UFP may be set.

“Continuous print elapsed time” (Condition (1))
The control unit 30 may control the air volume distribution adjustment according to the integration time from the start of continuous printing. As shown in FIG. 4, at the start of continuous printing, the amount of UFP diffused is large and decreases with time. On the other hand, the heat storage temperature of the paper in the paper discharge tray 81 increases as the load amount of the paper S increases, so that the tacking quality may deteriorate. Therefore, the suction unit 207 prioritizes the recovery of UFP in the initial stage in order to effectively use the air volume from the fan 207a (the state in FIG. 2), and gradually prioritizes cooling of the paper S as time passes (FIG. 3). It is better to control the air volume distribution adjustment so that

“Number of continuous prints” (Condition (2))
The control unit 30 may control the air volume distribution adjustment according to the total number of sheets from the start of continuous printing. As shown in FIG. 4, at the start of continuous printing, the amount of UFP diffused is large and decreases with time. On the other hand, since the heat storage temperature of the sheet S increases as the number of sheets from the start of continuous printing increases, the tacking quality may deteriorate. Therefore, the suction unit 207 prioritizes the recovery of UFP in the initial stage in order to effectively use the air volume from the fan 207a (the state in FIG. 2), and gradually prioritizes cooling of the paper S as time passes (FIG. 3). It is better to control the air volume distribution adjustment so that

“Amount of paper on the output tray” (Condition (3))
The control unit 30 controls the air volume distribution adjustment according to the detected stacking amount of the paper S based on information from the detecting unit 84 that detects the amount of the stacking paper S provided in the paper discharge tray 81. You may do it. As the detection unit 84, for example, the amount of the paper S can be detected using a photoelectric sensor or the like.

  As shown in FIG. 4, at the start of continuous printing, the amount of UFP diffused is large and decreases with time. On the other hand, since the heat storage temperature of the sheet S increases as the number of sheets from the start of continuous printing increases, the tacking quality may deteriorate. Therefore, the suction unit 207 prioritizes the recovery of UFP in the initial stage in order to effectively use the air volume from the fan 207a (the state in FIG. 2), and gradually prioritizes cooling of the paper S as time passes (FIG. 3). It is better to control the air volume distribution adjustment so that

"Single-sided / duplex printing information" (Condition (4))
The control unit 30 acquires information on single-sided printing or double-sided printing on the paper S, and in the case of single-sided printing, in the control of air volume distribution adjustment, it is preferable to perform control that gives priority to UFP collection over paper cooling ( The state of FIG.

  In contrast to the double-sided printing on the paper S, in the case of single-sided printing, the amount of heat stored in the paper S to be discharged is small, and tacking via a toner image occurs when the paper is loaded on the paper discharge tray 81. It is difficult to lower the paper cooling priority and increase the UFP collection priority accordingly.

“Temperature information of process unit in the system” (Condition (5))
The control unit 30 acquires information on single-sided printing or double-sided printing on the paper S, and acquires temperature information by the temperature / humidity sensor 54 provided in the image forming apparatus 1 in the case of double-sided printing. When the temperature becomes higher than the temperature, in the control of the air volume distribution adjustment, control that prioritizes the sheet cooling over the UFP recovery may be performed (state shown in FIG. 3). In the case of duplex printing, the sheet S after printing and fixing on one side again performs printing and fixing on two sides, so that the heat accumulated on the sheet S becomes a factor that raises the temperature in the image forming apparatus 1. Therefore, it is preferable to perform control so as to increase the priority of sheet cooling.

“External paper discharge unit installed” (Condition (6))
The control unit 30 determines whether or not the external paper discharge unit 400 (see FIG. 1) is attached to the image forming apparatus 1. If it is determined that the external paper discharge unit 400 is attached, the control unit 30 starts cooling the paper. Also, it is preferable to perform control (state shown in FIG. 2) giving priority to UFP collection. When the external paper discharge unit 400 is mounted, the transport path of the paper S from the fixing unit 80 to the paper discharge tray becomes long, and the paper temperature decreases while passing through the long transport path. As a result, the probability of occurrence of tacking decreases. Therefore, it is preferable to lower the paper cooling priority and increase the UFP recovery priority accordingly.

“Environmental temperature detection” (Condition (7))
The control unit 30 acquires the environmental temperature information of the area where the image forming apparatus 1 is installed by the external temperature detection unit 85, and when the temperature becomes higher than a predetermined threshold temperature, the UFP recovery is performed in the control of the air volume distribution adjustment. Control is given priority over paper cooling (state in FIG. 2), and when the temperature is lower than a predetermined threshold temperature, control for giving priority to UFP collection over paper cooling in the control of air volume distribution adjustment (FIG. 3). The state of Referring to FIG. 1, the external temperature detection unit 85 is provided outside the image forming apparatus 1.

  If the environmental temperature of the image forming apparatus 1 is high, the temperature of the paper cooling air also becomes high and the discharged paper is difficult to cool. Therefore, it is preferable to increase the priority of the sheet cooling. Further, the fixing unit 80 can reduce the heat applied to the paper S because the base paper temperature is high due to the environmental temperature. As a result, the amount of UFP generated is reduced, and the priority of UFP collection can be lowered.

"Width size detection" (condition (8))
The control unit 30 may control the air volume distribution adjustment according to the width of the paper S detected by the width size detection unit 86. Referring to FIG. 2, the paper discharge unit 201 is provided with a width size detection unit 86 that detects the width size of the paper S. When the width of the sheet S passing through the fixing unit 80 is small, a portion where the heat at the end of the fixing roller 80r is not taken away by the sheet S increases, and the temperature of the portion increases. Therefore, the amount of UFP emission generated from that portion is remarkably increased. For example, when the temperature rises by 10 ° C., the amount of UFP emission increases by an order of magnitude. Therefore, in the air volume distribution adjustment control, it is preferable to perform control that gives priority to UFP collection over sheet cooling (state in FIG. 2).

“Pass of paper S in paper discharge unit 201” (condition (9))
When the paper S is not passing through the paper discharge unit 201, the control unit 30 performs control to give priority to UFP collection over paper cooling in the control of air volume distribution adjustment. Specifically, even when the image forming apparatus 1 is operating, when the paper S does not pass through the paper discharge unit 82 of the paper discharge unit 201 (warm-up, job end, hold control, etc.), UFP collection is performed. Priority control may be performed (state shown in FIG. 2).

  While the UFP is always dissipated while the image forming apparatus 1 is operating, the sheet cooling is required only when the sheet S passes through the sheet discharge unit 201. Therefore, when the paper S has not passed through the paper discharge unit 82 of the paper discharge unit 201, the priority of the paper cooling is lowered, and control for giving priority to UFP collection is preferably performed (the state of FIG. 2). .

“Acquisition of information for color printing or monochrome printing 1” (condition (10))
The control unit 30 acquires information on color printing or monochrome printing, and in the case of monochrome printing, in the control of air volume distribution adjustment, it is preferable to perform control giving priority to UFP collection over sheet cooling (state in FIG. 2). . During continuous printing in black and white printing, the toner on the paper S is a single layer, so that tacking is unlikely to occur, so the priority of cooling the paper discharge can be lowered. Further, since the toner image on the sheet S is a single layer, less heat is applied to the sheet S by the fixing unit 80, which also leads to less occurrence of tacking. Accordingly, the priority of UFP collection can be increased.

“Acquisition of information for color printing or monochrome printing 2” (condition (11))
The control unit 30 acquires information on color printing or black and white printing, and in the case of black and white printing, in the control of air volume distribution adjustment, control that prioritizes paper cooling over UFP collection may be performed contrary to the above. . During continuous printing in monochrome printing, since the toner on the paper S is a single layer, less heat is applied to the paper S by the fixing unit 80. That is, since the temperature of the fixing roller 80r in the fixing unit 80 can be lowered, the amount of UFP emission is also reduced. Therefore, it is preferable to perform control (state shown in FIG. 3) giving priority to sheet cooling over UFP collection.

“Paper transport speed” (Condition (12))
When the low speed mode in which the paper conveyance speed is slow is selected, the control unit 30 may perform control that gives priority to UFP collection over paper cooling in the control of air volume distribution adjustment (state in FIG. 2). When the low-speed mode (thick paper mode / 1200 dpi mode or the like) is selected and the paper conveyance speed is low, the time for the paper S to pass through the paper discharge unit 201 after passing through the fixing unit 80 becomes longer. improves. As a result, it is preferable to perform control that gives priority to UFP collection by reducing the air volume for cooling the sheet.

"Utilization of tables"
In the control of the air volume distribution adjustment, the control unit 30 tabulates and holds the priority ratio when each factor overlaps with respect to the factor that determines whether paper cooling is given priority or UFP collection is given priority. The air volume distribution adjustment may be controlled based on the table. An example of the table is shown in FIG.

  “Continuous Print Elapsed Time” (Condition 1), “Continuous Print Number” (Condition 2), “Discharge Tray Stacked Amount” (Condition 3), “Single-Sided / Duplex Print Information” (Condition 4), “Apparatus” Priority information for paper cooling / UFP recovery even if multiple conditions are overlapped, such as "Internal process unit temperature information" (Condition 5), "External paper discharge unit installed" (Condition 6), etc. The ratio of the amount of air flowing through the sheet cooling duct or the UFP recovery duct may be adjusted based on the ratio determined and matrixed. FIG. 5 shows a table using the conditions (1) to (6). However, the above conditions (7) to (12) may be used, or an arbitrary condition may be selected as appropriate. May be formed.

  As described above, according to the image forming apparatus 1 in the present embodiment, it is possible to optimally distribute the air flow rate so that the UFP recovery and the sheet S can be appropriately performed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 Image reader part, 20 Printer part, 30 Control part, 33 Image memory, 34 Transfer drive motor, 35 Secondary transfer drive motor, 40C, 40K, 40M, 40Y Image forming part, 41C, 41K, 41M , 41Y photosensitive drum, 42C, 42K, 42M, 42Y charging charger, 43C, 43K, 43M, 43Y developer, 44C, 44K, 44M, 44Y cleaner, 45C, 45K, 45M, 45Y transfer roller, 50 paper feed unit, 51 Paper feed cassette, 52 Paper feed roller, 53 Registration roller, 54 Temperature / humidity sensor, 60 Intermediate transfer unit, 61 Drive roller, 62 Driven roller, 66 Screw, 68 Cleaning blade, 70C, 70K, 70M, 70Y Exposure scanning unit, 80 Fixing unit 80r fixing roller, 81 discharge tray, 82 discharge unit, 82r discharge roller, 84 detection means, 85 external temperature detection means, 86 width size detection means, 103 intermediate transfer belt, 104 secondary transfer roller, 105 intermediate transfer belt cleaner 107 Joint, 108 Waste toner box, 200 Panel portion, 201 Paper discharge portion, 202 Duct, 203 Paper discharge duct, 204 Merge portion, 205 Merge duct, 206 Air volume adjusting member, 207 Suction portion, 207a Fan, 300 Filter portion, 300f filter, 341 encoder, 400 external paper discharge unit, SE1 sheet detection sensor.

Claims (17)

An image forming apparatus including a fixing unit and a paper discharge unit,
A first duct, one end of which is connected to the fixing unit and sucks UFP released from the fixing unit;
A second duct, one end of which is connected to the paper discharge unit and sucks heat released from the paper located in the discharge unit;
A suction unit for drawing air from the fixing unit and the paper discharge unit through the first duct and the second duct;
An air volume adjusting member that adjusts the distribution of the air volume to the fixing unit and the paper discharge unit;
A control unit for controlling the air volume adjusting member;
With
The image forming apparatus, wherein the control unit performs control to distribute and adjust the air volume to the air volume adjusting member according to the air volumes required for the fixing unit and the paper discharge unit during continuous printing on paper. Including a junction where the other end of the first duct and the other end of the second duct are coupled;
The air volume adjusting member is provided at the junction,
The image forming apparatus according to claim 1, wherein air flowing in the first duct and the second duct is in the same direction.   The image forming apparatus according to claim 2, wherein the suction unit is provided on a downstream side of the merging unit.   The image forming apparatus according to claim 1, wherein the control unit controls the air volume adjusting member so that an air volume of the air flowing through the first duct and the second duct does not become 0%.   The image forming apparatus according to claim 1, wherein the control unit controls the air volume distribution adjustment in accordance with an integration time from the start of continuous printing.   The image forming apparatus according to claim 1, wherein the control unit controls the air volume distribution adjustment according to a total quantity of sheets from the start of continuous printing. The paper discharge unit includes a paper discharge tray and detection means for detecting the amount of paper stacked on the paper discharge tray,
The image forming apparatus according to claim 1, wherein the control unit controls the air volume distribution adjustment in accordance with a sheet stacking amount detected by the detection unit.   The control unit acquires information on single-sided printing or double-sided printing on paper, and performs control to give priority to UFP collection over paper cooling in the control of the air volume distribution adjustment during single-sided printing. The image forming apparatus according to 1. An internal temperature detecting means for detecting the internal temperature of the image forming apparatus;
The control unit acquires information on single-sided printing or double-sided printing on paper, and when performing double-sided printing, acquires temperature information by the internal temperature detection unit, and when the temperature becomes higher than a predetermined threshold temperature The image forming apparatus according to claim 1, wherein, in the control of the air volume distribution adjustment, control is performed so that paper cooling is given priority over UFP collection. Further including an external paper discharge unit,
The control unit determines whether or not the external paper discharge unit is attached, and when it is determined that the external paper discharge unit is attached, performs control to give priority to UFP collection over paper cooling. The image forming apparatus according to claim 1. An external temperature detecting means for detecting an external temperature of the image forming apparatus;
The control unit obtains temperature information by the external temperature detection means, and when the temperature becomes higher than a predetermined threshold temperature, the control of the air volume distribution adjustment performs control that gives priority to sheet cooling over UFP recovery. 2. The image forming apparatus according to claim 1, wherein, when the temperature becomes lower than a predetermined threshold temperature, control for giving priority to UFP collection over sheet cooling is performed in the control of air volume distribution adjustment. The paper discharge unit includes a width size detecting means for detecting a width size of the paper,
The image forming apparatus according to claim 1, wherein the control unit controls the air volume distribution adjustment according to a width of the sheet detected by the width size detection unit. If the paper does not pass through the paper output section,
The image forming apparatus according to claim 1, wherein the control unit performs control to give priority to UFP collection over sheet cooling in the control of air volume distribution adjustment. The control unit acquires information on color printing or monochrome printing,
2. The image forming apparatus according to claim 1, wherein in black-and-white printing, control for giving priority to UFP collection over sheet cooling is performed in the air volume distribution adjustment control. The control unit acquires information on color printing or monochrome printing,
2. The image forming apparatus according to claim 1, wherein in black-and-white printing, control for giving priority to sheet cooling over UFP collection is performed in the air volume distribution adjustment control.   2. The image forming apparatus according to claim 1, wherein when the low speed mode in which the paper conveyance speed is slow is selected, the control unit performs control to give priority to UFP collection over paper cooling in the control of air volume distribution adjustment. .   In the control of the air volume distribution adjustment, the control unit tabulates and holds the priority ratio when each factor overlaps with respect to a factor for determining whether to give priority to sheet cooling or UFP recovery. The image forming apparatus according to claim 1, wherein the air volume distribution adjustment is controlled based on the table.

Images